Electrodeposition of nickel



ELECTRODEPOSITION F NICKEL Henry Brown, Huntington Woods, Mich, assignor to The Udylite Research Corporation, Detroit, Mich, a corporalio'n of Michigan NO Drawing. Application April 27, 1956, Serial No. 580,990

4 Claims. (Cl. 204-49) This invention relates to the electrodeposition of nickel from an aqueous acidic bath.

'One object of this invention is to decrease the grain size and increase the luster of the nickel deposit.

A second and major object is the electrodeposition of brilliant, highly lustrous, ductile nickel plate.

It has been found that these objects can be accomplished by the use of certain organic compounds in the aqueous acidic nickel baths.

The first object can be accomplished by the addition to the Watts type of nickel bath or its modifications, of certain organic compounds which contain unsaturated linkages, such as the aldehydic (and ketonic carbonyl), the olefinic type of unsaturated bond, double or triple, and the unsaturated carbon to nitrogen bond, double or triple, i. e.

Compounds in the bath containing such groups cause the nickel plate to be very fine grained (even though cloudy and milky in appearance) and show marked increasing lustre With continued plating.

However, not all unsaturated linkages produce the desired effects, for example, unsaturated bonds not connected to carbon, for example, N=O, N=N. Also the unsaturated bonds carbon to carbon, carbon to oxygen, or carbon to nitrogen, Where an OH, or --NH2, or -NH group is also attached to the carbon atom carrying the unsaturated bond, for example:

It was further found that the second object, the production of brilliant highly lustrous ductile nickel plate, could be accomplished by the use in conjunction with the active unsaturated groups (1), another, difierent functional group, namely the methylene sulfone group as exemplified by aryl sulfonamides and sulfonimides, or aryl sulfonic acids. Compounds with either group alone in the bath give no obvious indication of the remarkably different and enhanced result which occurs when both groups are present. 7

The first object mentioned above can also be accomplished by the addition to the Watts type of nickel bath or its modifications of certain amides carrying an unsaturated olefinic group. The presence of these particular amides, which are more specifically illustrated by the compounds set forth in Table III, may be designated generally by Formula A FORMULA A an i r H*C=CCNR4 where Ri and R2 are selected from the group consisting ofhydrogen, acetyl, chlorine, bromine, methyl, methyl ice carboxy, carbonyl, cat-boxy and aldehydo, phenyl and turyl and the chloro, bromo, acetyl, methyl, carboxy, amino, methoxy, ethoxy, dioxymethylene, carbonyl amido, hydroxy and ethyl substitution products of phenyl' and furyl; R3 and R4 are selected from the group consisting of hydrogen, methyl, methylene, methylol, formyl, acetyl, amino, amido, imido, carboxy, carbonyl, 'benzoyl and nicotinoyl radicals. The types of compounds which are encompassed by Formula A are illustrated in the compounds designated A, B, C and D.

COMPOUND A When R1, R2, R3 and R4 are hydrogen, we have ll CH =CHCNHz Acrylamide COMPOUND B When R1 is phenyl, R2, R3 and R4 are hydrogen, we have Cinnamic amide COMPOUND C Where R1 is methyl carboxy, R2, R3 and R4 are hydrogen, we have Monomethyl maleic acid monoamide (methyl ester of maleamic acid) COMPOUND D When R1 is carbonyl, R2 and R3 are chlorine and R4 is hydrogen, we have Mucoehloric acid amide plish the same result on steel polished, for example, with, 200 emery or on top of matte (but unburnt) copper plate;

.of I).00.Q3"-..O005" thicknessandyield inthese cases plate of dull and grey appearance.

The compounds carrying the active unsaturated groups a'(.olefinie,'aldehydic, etc.) while giving a different type of plate .than that produced .by the aryl sulfones, neverthe- .1ess,::-give. .atbest -.a cloudy-plate ;on either bufied .or matte metal. Their rate of improvement of lusterof the base metal :is, however, faster than that produced by aryl sulfonamideszor aryl sulfonic acids.

If, howeventhese two different groups are used together, :a brilliant mirror-likedeposit can be obtained even on the-matte copper deposit. The-result is very striking from a comparison of theresults' obtained with either group alone in the bath. This is .best illustrated by an example.

If fur-furalis added to aWattsbath in the concentration of about 0.7 g./ 1., a brittle, poorly adherent, fine-grained, cloudy deposit is obtained and seems to be covered with an iridescent film which stains easily. On the addition of 2 g./l. of an aryl fulfone, for example, o-benzoyl sulfimide, a very brilliant, ductile, adherent plate is ob- .tained. Thus not only has the tolerance of the bath been remarkably increased to larger concentrations of the furfural, but there has resulted a plate of striking brilliance.

Furthermore, it is found that with continued plating, the furfural is depleted more slowly in the presence of the aryl sul'r'one. On analysis of the plates for carbon in the case of furfural alone in "a bath containing 250 g./l. of

NiSO4.7H2O, 60 g./l. of NiCl2.6I-I2O, and 40 g./l. of

H3303, and in the case of the same, concentration of furfural used together with 2 g./l. of o-benzoyl sulfimide, it is found that about twice as much carbon is present in the plate with furfural alone (i. e. about 0.28% compared to about 0.17%); the plates were run at the same current density, 30 amps/ sq. ft. average.

Mixing any two brighteners in the bath will not give rise to a plate of remarkable brilliance, for example, in mixing an active aldehyde with [zinc or cadmium in their cmployable concentrations. Instead, there is practically no improvement in brightness, but an increase in dull areas anda definite loss of ductility and bond, that is, the latter two types of materials act similarly though'not identically in the bath. The active unsaturated compounds, such as furfural, crotonaldehyde, diallylarnine,

allyl alcohol, have in general the characteristic of producing marked changes in the appearance and character of the plate with increasing concentrations of the unsaturated compounds. As their concentration is increased, the plating of nickel in the very low current densities is practically stopped and with further increase in concentration, streaked, peeled, brittle plate results. The aryksulfones in general do not have critical concentrations, and they produce practically no further results after their optimum concentration is reached, i. e.,

they do not produce peeled, streaked plate at any concentration-"and the baths always platemore easily in the low current density areas than the. plain nickel bath. This phenomenon, as well as their life in the bath (which differs extremely), indicates that there is a different rate of reduction of these two types of compounds at the nickel cathode with respect to the nickel ion. In the case of the active unsaturated. compounds (olefinic, aldehydic, etc.) there is preferential reduction ofthe unsaturated compound with respect to the nickel ion, whereas with the aryl sulfones, the nickel ion is reducedprefereritially. Thus the :effect of the aryl sulfonesin the nickel bath on the plating out of small percentagesof other ions more easily reduced than the nickel, i. e. Cu++,' 'Zn Cd 'i, etc. is also-more readily understood. The

3'? 'ationof the reduction with the variation-ofthecathode potentials between adjacentrhigh and-lowpoints will account for the rate of brightening, or smoothening out? effezh etc. of the various addition agents.

-'I heuniqueness of the arylsulfones, or broadly the I =C-S compounds, seems to be mainly tied up with the rate of reduction of the positive valent sulfur compound to negative valent sulfur compound, and the mechanism of its deposition. The fact that with wnaphthalene sulfonamide as the only organic compound in the hath, not only is the odorof naphthalene apparent at the cathode duringthe plating, but the analysis of the plateshow's the presence of carbon as well as sulfur, which indicates that the'me'chanism of the reduction is not of the simplest form.

It is not the sulfonegroup alone that is responsible for the effect of the aryl sulfones because the saturated alkyl sulfones are not nearly as "efiective 'a'sthe aryl sulfones.

Certain substituting groups on the ring detract from the beneficial effect of the I =CS group, i. e., hydroxy groups on the ring, nitro groups, and too many alkyl groups on the ring which introduces insolubility and colloidality.

The benzene and toluene sulfonamides and ortho benzoyl sulfimide are more effective than aryl monosulfonic acids, especially of the benzene series, nevertheless the latter, even though they may not produce bright plate on buffed metals, will give brilliant ductile plate when used in combination with the active unsaturated compounds.

The various compounds which carry-one or more active unsaturated groups or combinations differ greatly in their degree of effectiveness in a bath when used alone or in conjunction with the aryl sulfone compounds. The compounds which give the most beneficial effects and are the least critical when used alone are in general not the ones that are the most effective when used with the aryl sulfones. V

The effectiveness of the unsaturated compounds is greatly dependent on the type and number of unsaturated groups, on their positions in the molecule, and the pres ence of other groups. For example, the allyl group is much more effective than the beta-methyl allyl. The allyl group is as effective or even more effective than the aldehyclic carbonyl.

In the discussion below of the organic compounds containing unsaturated linkages, it is understood that the description relates to these compounds when used with the aryl sulfones in an acid nickel plating bath.

Olefinic unsaturated c0mp0unds.'-Un'satu'rated* alcohols are not as effective as unsaturated aldehydes or unsaturated ketones, which is to be expected from the fact that the saturated alcohols have no effect in the bath when used in the same concentrations. Allyl alcohol is superior to butyraldehyde and also to furfuryl alcohol. The unsaturated amines are very effective. The three allyl amines, tri-, di-, and mono-allyl amine are the best of the unsaturated amines. The saturated aliphatic amines, on the other hand, .areeither inefiectiveor harmful. The unsaturatedamides, particularly allyl urea, are very 'efiective and when used alone in the bath, somewhat less critical than the unsaturated amines. The saturated areas, such as propyl or butyl urea of urea itself have no effect in similar or larger concentrations. Other unsaturated c0mp0unds.--The triple bon CEC-- is exceedingly active and only traces of compounds carrying it,such as dimethylethynyl carbinol, can be used even with the aryl sulfones. The aliphatic CEN compounds such as. propionitrile are also exceedingly active and the slightest excess prevents plating at very low current densities-and causes highly streaked, brittle, non-adherent plate. Thecyano aryl compounds such as cyanobenzoic acid, cyano-benzene sulfonic acid are much less active and do not show the critical eflects that the aliphatic '60, thus showingagainhow the properties of even themost active of the unsaturated groups may be altered by various substitutions to give the desired amount or degree of eflEect. Furthermore, in the same way, the double bond is not as critical as the -C- -C--, also the group is not as critical as the --CEN. For example, the

compounds: pyridine, quinoline, phenosafranine, Nitron (1,4 diphenyl-endanilo-triazoline), etc have the linkage is so much more active than the I linkages that it produces the desirable effects even when the entire group is in a ring, as in pyridine, phenosafranine, etc. whereas the groups are not efiective when part of an aromatic ring. In fact the compounds carrying the and J;= group (wherein the latter is in a ring and attached by its carbon to another carbon or a tertiary nitrogen) can be used in very small concentrations together with an aryl sulfone to give a brilliant plate, and moreover depletes at a slower rate than do the active olefinic compounds as 1 carbon analysis of their plates also shows.

The concentration of a compound represented by Formula A or a mixture thereof which may be advantageously employed is not critical in any concentration up to saturation, and may be used at concentrations between about 0.1 to about 2.0 grams/liter, the preferred concentration being .6-1.2 grams/liter.

In keeping with their chemical activity, the higher the temperature of the bath, the more active are the unsaturated groups in the bath and smaller concentrations of compounds carrying them must be used. Furthermore, they function best at the higher pH values of the nickel bath, that is, 3.0 to 5.2, and their effectiveness in mos-t cases drops rather suddenly when the pH is lowered past a certain value (in general, at a pH below 3.0 or 2.5, depending on the type of unsaturated compound and on the temperature). The lower the temperature, the higher are the pH values that should be used, and conversely.

The best cathode film butter is boric acid and it is important to keep its concentration high (over 30 grams/liter), especially in the warm baths. Other buffers may be used in small amounts (1 to 5 grams/liter) with the boric acid with beneficial efiects, such as formic, citric, fluoboric acids, etc., but they are not recommended to be used alone.

In the use of a compound represented by Formula A alone in the bath, or in the presence of the aryl sulfones,

ammonium salts should be kept at a minimum. A concentration of zinc and copper ions in the bath should also be kept as low as possible. This is especially desirable where the concentration of aryl sulfones are low in the bath or the latter compounds are absent.

The baths may be operated at pH values ranging from 2.0 to 5.5 and temperatures ranging from 20 C. to 70 C. and the preferred current density ranges may be from 5 to 150 amps/sq. ft., depending on the agitation, the temperature of the bath and the concentration and the type of nickel salts. The benzene sulfonamides and sulfonimides may be used efiectively in concentrations of from 0.05 gram/liter to saturation. Some of the baths are remarkably free from pitting without the use of auxiliary surface-active materials. This is especially true where the baths are kept clean and free from excessive contamination. Otherwise a straight chain, alkyl benzene sulfonate or a wetting agent such as lauryl alcohol sulphate or iso-octyl alcohol sulphate is desirable.

' In Table I are listed preferred bath compositions. Table l Nlso-t. NiCla. HBBO; Ni(BFi)l, Temp. Opti- 611,0, g./l. 0H o, g./l. g./l. o. mum pH In the case of the very active unsaturated compounds and specifically dimethylethynyl carbinol, trace quantities as little as 0.001 to 0.01 gram/liter give optimum results with benzene sulfonamides and benzene sulfonimides.

In Table H are listed representative examples of organic sulfonamides, sulfonimides and sulfonic acids which may be employed in conjunction with the addition agents of Table III.

14. Hydroxymethyl benzene sulfonamide--- 0.1-2

15. Vinyl sulfonamide 4-12 16. Allyl sulfonamide 4-12 17. Benzene sulfonic acids (mono-, di-, and

tri-) 1-15 18. p-Brom benzenesulfonic acid 3-6 19. Benzaldehyde sulfonic acids (0, m, p) 2-6 20. Diphenyl sulfone sulfonic acid 1-8 21. Naphthalene sulfonic acids (mono-, di-,

tri-) -4 1-8 22. Benzene sulfohydroxamic acid l-S 23. p-Chlor benzene sulfonic acid.. 1-15 24. Diphenyl sulfonic acid l-S 25. m-Diphenyl benzene sulfonic acid 1-4 26. 2- chloro 5 sulfobenzaldehyde 1 -5 27. m-Benzene disulfonamide 0.5-1 28. Allyl sulfonic acid 4-12 29. Cinnamyl sulfonic acid 0.1-8

30. Cinnamyl sulfonamide 0.1-3

In T e lla i ed rep e a e examp es. of spa cifiecompounds which are suitable for the purposes of this invention, when used alone in a Watts type nickel bath or in combination with organic sulfonamides, sulr'onimides and sulfonic acids of Table II.

Table III Opti- Cornmum pound Unsaturated amides cone,

N grams/ liter 1 Acrylamide I e 0.1-1. 2 2. N-aeetyl aerylamide.. 0. 1-1. 2 3 Cinnarnic amide 0. 1-1. 2 4. o-Ghlorocinnamle amide 0. 1-1. 2 5. B-Ohloroacrylamide 0.1-1. 2 6, Z-lnmnacrylamide.... t-. 0. 1.1. 2 7. p-Methoxyclnnamic amide... 0. l1.2. 8..- Math-acrylamide 0. 1-1. 2 9 N-anetyi acrylamide. 0. 1-1. 2 10 Fumaramide (di-amide) 0. 1-1. 2 11. Cnloiofumaramide 0. 1-1. 2 12 Chloromaleicamide 0. 1-1. 2 13 Maleic imide 0. 1-1. 2 14-. Phenyl maleie irnide 0. l-l. 2 15 N-phenyl maleic imide 0. 1-1. 2 a, B, Di-phenyl maieic imide 0. 1-1. 2 0:, B, Di-phenyl maleie amide (til-amide) 0. 1-1. 2 N-nicotinoyl acrylamide 0.1-1; 2 N-allyl acrylamide 0. 1-1. 2 N-methyl acrylamide 0. 1-1. 2 N-benzoyl acry1amide.. 0. 1-1. 2 Atropyi amide 0. 11. 2 Mucoehloric acid amide" 0. Mucobromic acid amide 0;

N-tertiary Butylacrylamide..- 0. N-aeryiourea O. flipe ony ry a l s 0 1 o-Hydroxy einnamie amid 0. .2 osMethoxy einnamic amide 0. :2 pECarbOnyl-amide cinnamic amide (p-Carbonyle amide phenylacryiamide) 0. 1-1. 2 o-Acetyl einnamle amide 0. 1-1. 2 Mono 2emethoxyethyl maleic aeidmonoamide- 0.1-1.2 Allyl urea (1.1-0.6 Nemethylol acrylamide 0. 1-1. 2 N-N' methylene bis-aerylarni t). 1'1.2

Concentrations of allylurea greater than 0.6 grams/ liter can be used, and in combination with benzene sulfonamides and/or benzene sulfonimides when greater brightness is desired concentrations of allyl ureaup to about 2 grams/liter are satisfactory, although as 2 grams/liter is approached, ductility decreases slightly.

Although Table III shows the optimum concentration of the compounds therein listed to be between 0.1 and 1.2 grams/liter, these compounds may be used in concentrations up to saturation, especially when used in conjunction with benzene sulfonarnides, toluene sulfonamides and o-benzoyl sulfimide. In general, a concentration higher than about 2.5 grams/liter is unnecessary.

It will be understood that any of the compounds listed in Table III may be used separately in a Watts type nickel bath or in combination'with any of the organic sulfonamides, sulfonimides or sulfonic acids of Table II in any of the typical baths set forth in'TableI. For purposes of further illustration, the examples given below set forth certain preferred embodiments of the invention.

EXAMPLE III Grams/liter. NiSO4.6H2O 50 NiCl2.6I-I2O 250 HsBOa 7 40-50 Z-furanacrylaniide 0.8 o-Benzoyl sulfimide 1-2 oor p-Toluene sulfonamide 1-3 EXAMPLE IV Grams/liter Ni(BF4)z 10020O HaBOa Fumaramide 0.8-1.5 o-Benzoyl sulfimide 1-2.

1 Saturation.

EXAMPLE V NiSO4.6HzO grains/liter 250 NiCl2.6H2O .do -75 HaBOa d0.. 35-40 o-Benzoyl sulfimide do 0.1-2 Allyl urea do 0.l-0.6 Temperature C..- 65 pH 2.54.5

EXAMPLE VI NiSO4.6H2O grarns/liter 250 NiCl2.6 H2Q do 35-75 HaBOs do 35-40 o-Benzoyl sulfimide do 0.1-2 N-Methylol acrylamide .do 0.l1.2 Temperature C 40-65 pH 2.5-4.5 EXAMPLE VII NiSO4.6H2O grams/liter 250 NiC12.6H2O do 35475 HaBOs dO 35-40 o-Benzoyl sulfimide do 0.1-2 N-N' methylene bis-acrylamide do (Ll-1.2. 1 Temperature C 40-65 pH 2.5-4.5

The addition agents of' this invention may consist of a compound or mixture of compounds represented by Formula A as such, or may consist of an admixture of at least one compound represented by Formula A and at least one compound selected from the group consisting of organic su-lfonamides, sulfonimides and sulfonic acids.

This application is a continuation-in-part of my copending application, Serial No. 374,418, filed August 14, 1953. Serial No. 374,418 is a continuation-in-part of Serial No. 749,344, filedMay 20, 1947, which is now abandoned. Application Serial No. 749,344 is a continuation-in-part of application Serial No. 366,385, filed November 20, 1940, and the present application is in part a substitute for application Serial'No. 366,385, which is now abandoned.

What is claimed is:

1. A bath for electrodepositing ductile bright nickel plate comprising an aqueous acidic nickel solution consisting essentially ofa material selected from the group consisting of nickel sulfate, nickel chloride, and a mixture of nickel sulfate and nickel chloride, having dissolved therein at leastone compound selected from the group consisting of benzenev sulfonamides and benzene sulfonimidesfiri combination with an amount sufficient to enhence brightness of allylurea.

, 2. A bath for electrodepositingductile. bright nickel plate comprising an aqueous acidic nickelsolution consisting-essentially of a material selected from the groupv 7 consisting offnickelsulfate, nickel chloride-and a-mixture of nickel sulfate, and nickel chloride, having dissolved therein at least one compound selected from the group consisting of benzene sulfonamides and benzene sulfonimides in combination with about 0.1 to about 0.6

gram/liter of aliyl urea.

3. A method for electrodepositing ductile bright nickel which comprises electrodepositing nickel from an aqueous acidic nickel solution consisting essentially of a material selected from the group consisting of nickel sulfate, nickel chloride and a mixture of nickel sulfate and nickel chloride having dissolved therein at least one compound selected from the group consisting of benzene sulfonamides and benzene sulfonimides in combination with an amount sufficient to enhance brightness of allyl urea.

4. A method for electrodepositing ductile bright nickel which comprises electrodepositing nickel from an aqueous 10 acidic nickel solution consisting essentially of a material selected from the group consisting of nickel sulfate, nickel chloride and a mixture of nickel sulfate and nickel chloride, having dissolved therein at least one compound selected from the group consisting of benzene su1fonamides and benzene sulfonimides in combination with about 0.1 to about 0.6 gram/ liter of allyl urea.

References Cited in the file of this patent Raub et al.: Metal Finishing, June 1940, pages 315-316. 

1. A BATH FOR ELECTRODEPOSITING DUCTILE BRIGHT NICKEL PLATE COMPRISING AN AQUEOUS ACIDIC NICKEL SOLUTION CONSITING ESSENTIALLY OF A MATERIAL SELECTED FROM THE GROUP CONSISTING OF NICKEL SULFATE, NICKEL CHLORIDE, AND A MIXTURE OF NICKEL SULFATE AND NICKEL CHLORIDE, HAVING DISSOLVED THEREIN AT LEAST ONE COMPOUND SELECTED FROM THE GROUP CONSISTING OF BENZENE SULFONAMIDES AND BENZENE SULFONIMIDES IN COMBINATION WITH AN AMOUNT SUFFICIENT TO ENHANCE BRIGHTNESS OF ALLYL UREA. 